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<script>
    let userId;

    function SET_USERID(){
        //本地存储有没有用户信息
        userId = localStorage.getItem('USERID')

         //本地存储没有用户信息，生成一份存储
        if(!userId){
            userId = Math.random();
            localStorage.setItem('USERID',userId)
        }

        return userId;
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    console.log(SET_USERID())
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